1 Phenoxybenzamine (Oral Route): A Summary

Brand: Dibenzyline

Generic: Phenoxybenzamine (Oral Route)

Brand name:


Phenoxybenzamine is an antihypertensive used for the treatment of hypertension secondary to pheochromocytoma.

This drug blocks the effects of certain chemicals which cause high blood pressure in the body. This drug requires a prescription.

2 What to Know Before Using

Before taking this drug, the risks and benefits for your body should be discussed with your healthcare provider.

Inform your healthcare provider for any allergic reactions to these drugs or any other drugs, foods, dyes, preservatives, or animals.

Carefully read the label of non-prescription drugs for any possible allergic reaction or contraindications. This drug is not expected to cause different side effects or problems in children than it does in adults.

This drug can cause dizziness, lightheadedness, or reduced tolerance to cold temperatures in the elderly due to their increased sensitivity. In addition, phenoxybenzamine may reduce tolerance to cold temperatures in elderly patients.

Adverse effects have been reported in animal studies but studies in pregnant women or animals are still inadequate. Infant risk is still undetermined when using this drug during breastfeeding.

Discuss with your healthcare professional about the potential risks and benefits of taking this drug while breastfeeding.

Drugs should not be taken together to prevent any interactions but in necessary cases inquire your healthcare provider regarding the adjustments in dosage or any other necessary precautions to prevent any unwanted side effects.

Inform your healthcare professional if you are taking any other drugs such as:

  • Asenapine
  • Tadalafil
  • Acebutolol
  • Alprenolol
  • Atenolol
  • Betaxolol
  • Bevantolol
  • Bisoprolol
  • Bucindolol
  • Carteolol
  • Carvedilol
  • Celiprolol
  • Dilevalol
  • Esmolol
  • Labetalol
  • Levobunolol
  • Mepindolol
  • Metipranolol
  • Metoprolol
  • Nadolol
  • Nebivolol
  • Oxprenolol
  • Penbutolol
  • Pindolol
  • Propranolol
  • Sotalol
  • Talinolol
  • Tertatolol
  • Timolol
  • Vardenafil

Intake of specific food or using alcohol or tobacco with this drug is associated with an increased risk of certain side effects.

Your healthcare professional can give you special instructions about the use of food, alcohol, or tobacco.

Inform your healthcare provider for any other medical problems such as angina, heart or blood vessel disease, kidney disease, lung infection, or recent heart attack or stroke.

3 Proper Usage

To prevent any side effects, take this drug exactly as directed on the label or as prescribed by your healthcare professional. The dose of this drug will be variable for different patients.

The directions on the label or the prescription by your healthcare professional should be followed. The dosage of this drug you take depends on the medical problem for which you are using this drug.

Adults with high blood pressure caused by pheochromocytoma are initially given 10 milligrams two times a day. Then, your healthcare professional may increase your dose to 20 to 40 mg two or three times a day.

The dose in children is based on body weight and must be determined by your healthcare professional. The usual starting dose is 0.2 mg per kilogram of body weight taken once a day.

Then, your healthcare professional may increase your dose to 0.4 to 1.2 mg per kg of body weight a day. This is divided into three or four doses.

A missed dose should be taken as soon as possible. However, skip the missed dose and go back to your regular dosing schedule if it is almost time for your next dose.

Store the drug in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing. Keep out of the reach of children.

Dispose any outdated or expired drugs and ask your healthcare professional for the proper disposal of the drugs.

4 Precautions to Take

Regular visits should be made to your healthcare provider to track your progress and to monitor the effectiveness of the drug. Unwanted effects can be screened using blood tests.

Inform your healthcare professional immediately if you have symptoms of anaphylaxis such as:

  • rash
  • itching
  • hoarseness
  • lightheadedness
  • dizziness or fainting
  • trouble breathing
  • trouble swallowing
  • any swelling of your hands, face, mouth or throat after using this drug

This drug may cause some people to become dizzy, drowsy, or have blurred vision.

Make sure you know how you react to this drug before you drive, use machines, or do anything else that could be dangerous if you are dizzy, not alert, or not able to see well.

This drug may cause dryness in the mouth, nose, and throat. It is recommended to use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute for temporary relief of mouth dryness.

Check with your medical health care professional or dentist if your mouth continues to feel dry for more than 2 weeks to prevent any chance of dental disease, including tooth decay, gum disease, and fungal infections.

Check with your healthcare professional before you take any other prescription or nonprescription drugs, and herbal or vitamin supplements.

5 Potential Side Effects

It is still unknown whether this drug increases the risk of tumors in humans. Some side effects may occur that usually do not need medical attention.

As your body adjusts to the drug, the side effects will slowly disappear. Ask your healthcare professional about ways to prevent or reduce some of these side effects.

If any of the following side effects persists or are inconvenient, or if you notice any other effects, or if you have any questions about them, consult with your health care professional.

Report any side effects to the FDA hotline at 1-800-FDA-1088.